cue/parser: allow attributes before package and import clauses
This is to facilitate "build tags".
Change-Id: I8ea85d4f1339a3584e7763d342715b8fad2fe48f
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/7062
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/doc/ref/spec.md b/doc/ref/spec.md
index f7f0326..8d7f2eb 100644
--- a/doc/ref/spec.md
+++ b/doc/ref/spec.md
@@ -2899,7 +2899,7 @@
to a data format
```
-SourceFile = [ PackageClause "," ] { ImportDecl "," } { Declaration "," } .
+SourceFile = { attribute "," } [ PackageClause "," ] { ImportDecl "," } { Declaration "," } .
```
```
